Sphalerite, processing

Zinc occurs most abundantly in tire mineral. Sphalerite, ZnS, which is roasted to produce the oxide before the metal production stage. The products of the roast are then reduced by carbon to yield zinc oxide and CO(g). In the older process, tire Belgian retort process, the metal oxide and carbon are mixed together in a reactor which allows the indirect heating of the charge to produce the gaseous products followed by tire condensation of zinc at a lower temperature in a zone of the reactor which is outside the heating chamber. The carbon monoxide is allowed to escape from the vessel and is immediately burnt in... 

Zinc Zinc is processed very similarly to copper and lead. The zinc is bound in the ore as ZnS, sphalerite. Zinc is also obtained as an impurity from lead smelting, in which it is recovered from the blast furnace slag. 

Sulfur is widely distributed as sulfide ores, which include galena, PbS cinnabar, HgS iron pyrite, FeS, and sphalerite, ZnS (Fig. 15.11). Because these ores are so common, sulfur is a by-product of the extraction of a number of metals, especially copper. Sulfur is also found as deposits of the native element (called brimstone), which are formed by bacterial action on H,S. The low melting point of sulfur (115°C) is utilized in the Frasch process, in which superheated water is used to melt solid sulfur underground and compressed air pushes the resulting slurry to the surface. Sulfur is also commonly found in petroleum, and extracting it chemically has been made inexpensive and safe by the use of heterogeneous catalysts, particularly zeolites (see Section 13.14). One method used to remove sulfur in the form of H2S from petroleum and natural gas is the Claus process, in which some of the H2S is first oxidized to sulfur dioxide ... 

In the profiles of the core from the industrial area, mercury displays the highest accumulation. Mercury in this area, close to the industrial district, has probably derived from a large chloralkali plant which has employed mercury cathodes since the fifties. Whereas, at present, very severe measures are taken to prevent mercury spills into the Lagoon, in the past, polluted waters and solid materials were discharged almost untreated. In the most superficial strata a marked decrease in the accumulations is, in fact, recorded. Lead and Cd accumulations are lower here by a factor of 5-10. The presence of cadmium in the sediments of the Lagoon has been referred to sphalerite (ZnS) processing on the basis of a strict concomitant... 

Mizuta, T. (1988) Compositional homogenization of sphalerite in hydrothermal ore deposits of Japan by post-depositional diffusion processes with particular reference to metamorphosed Besshi-type deposits. Mining Geology, 38, 263-278. 

There are new ideas and experiments on the rTCA cycle. A group from Harvard University studied some reaction steps in the rTCA cycle which were kept going by mineral photochemistry. The authors assumed that solar UV radiation can excite electrons in minerals, and that this energy is sufficient to initiate the corresponding reaction steps. In this photocatalytic process, semiconductor particles were suspended in water in the presence of a zinc sulphide colloid (sphalerite) the experiments were carried out in a 500 mL reaction vessel at 288 K. Irradiation involved a UV immersion lamp (200-410 nm) in the photoreactor. Five reactions out of a total of 11 in the rTCA cycle were chosen to check the hypothesis ... 

Several reviews on ore processing by flotation are available.17-21 In addition to providing details of the chemistry of collectors they describe the use of activators and depressants. The former usually convert the surfaces of an ore particle which does not bind strongly to conventional collectors to one that does. The addition of Cu2+ ions to enhance the flotability of minerals such as sphalerite, a zinc sulfide, has been exploited for some time.4 Formation of a surface layer of CuS has been assumed to account for this, but the mechanisms and selectivities of such processes continue to be investigated.18,22,23... 

Pb2Sb206(0,0H)), sphalerite (ZnS), and smithsonite (ZnC03) were identified. These minerals are derived from both geogenic and technogenic processes in the Mezica mining district. 

According to the analyses of the above cyclic voltammogram results, it can not be determined that the active products at the sphalerite surface is CU2S or CuS. However this phenomenon may imply the essence of the process itself. It suggests that in the ZnS - CUSO4 system the Cu concentration in active products keeps equilibrium with that in solution, which is strictly controlled by chemical potential. When the working potential is lower than the rest potential of CuS, the... 

In the actual flotation system, the activators on the sphalerite surface are some copper sulphide compounds containing different amounts of copper, namely some non-chemometric cupric sulphide. Based on the electrochemical theory of chalcocite in geologically minerogenic process, they may be chalcocite (CU2S), diulerite(Cui.96S), Cui,7i i.g2S, anilite(Cui.75S), geerite(Cui.6oS), spionkopite (CU1.40S), Cul.l2S and covellite (CuS). 

Costa, M. C., Botelho, do Rego A. M., Abrants, L. M., 2002. Characterization of a natural and an electro-oxidized arsenopyrite a study on electro-chemical and X-ray photoelectron spectroscopy. Inter. J. Miner. Process, 65 83 - 108 Dai Jingping, Sun Wei, Cao Limei, Hu Yuehua, 2000. Influence of mechanical excitation on adsorption of sodium diethyl dithioformate on galena and sphalerite. Trans. Nonferrous Met. Soc., China, 10 101 - 105... 

Fereshteh, R., Caroline, S., James, A. F., 2002. Sphalerite activation and surface Pb ion concentration. Inter. J. Miner. Process, 67 43 - 58 Fierro, R. E., Tryk, D., Scherson, D., Yeager, E., 1988. Perovskite-type oxides oxygen electrocatalysis and bulk structure. Journal of Power Sources, 22 (3 - 4) 387 - 398... 

Kartio, I. J., Basilio, C. I., Yoon, R. H., 1996. An XPS study of sphalerite activation by copper. In R. Woods, F. Doyle, P. E. Richardson (eds.), Electrochemistry in Mineral and Metal Processing IV. The Electro-Chemical Society, 25 - 34 Kelebek, S., 1987. Wetting behaviow, polar characteristics and flotation of inherently hydrophobic minerals. Trans. MM, Sec. C, 96 103 - 107... 

Trahar, W. J., Senior, G. D., Heyes, G. W., Creed, M. D., 1997. The activation of sphalerite by lead—a flotation perspective. Inter. J. Miner. Process, 49 121 - 148 Usui, A. H. and Tolun, R., 1974. Electrochemical study of the pyrite-oxygen-xanthate system. Inter. J. Miner. Process, 1 135 - 140... 

Vathsala, K. A. Natarajan, 1989. Some electrochemical aspects of grinding media corrosion and sphalerite flotation. Inter. J. Miner. Process, 26(3 - 4) 193 - 203 Walker, G. W., Stout, J. V. Ill, Richardson, P. E., 1984. Electrochemical flotation of sulphides reaction of chalcopyrite in aqueous solution. Inter. J. Miner. Process, 12 55 - 72 Wang Dianzuo, 1983. Structure and reactivty of organic depressant on flotation. Nonferrous Metals, (2) 47-51... 

Yelloji Rao M. K. and Natarajan, K. A., 1989c. Effect of galvanic interaction between grinding media and minerals on sphalerite flotation. Inter. J. Miner. Process, 27(1 - 2) 95 - 109 Yelloji Rao M. K. and Natarajan, K. A., 1990. Effect of electrochemical interactions among sulphide minerals and grinding medium on the flotation of sphalerite and galena. Inter. J. Miner. Process, 29 175 - 194... 

Yoon, R. H., 1981. Collectorless flotation of chalcopyrite and sphalerite by using sodium sulphide. Inter. J. Miner. Process, 8 31 - 48... 

Zhao Jing et al., 1988. Research on the mechanism of chalcopyrite depressed by sodium mercaptoacetic. Nonferrous Metals (part of mineral processing), (3) 42 - 45 Zhuo Chen and Yoon, R. H., 2000. Electrochemistry of copper activation of sphalerite. Inter. J. Miner. Process, 58 57 - 66... 

The zinc that is produced today starts as the zinc sulfide (ZnS) minerals zinc blende or sphalerite or from zinc carbonate (ZnCO ) known as smithsonite or calamine. In the electrolytic process, these minerals are dissolved in water to form the electrolyte in the cell where the zinc cations are attracted and collected at the cathode and deposited as a dull, brittle type of zinc. 

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